Managing Bats in Buildings
Dianne OdegardOutreach AssociateBat Conservation
International
Buildings & other structures give bats what they need
• Crevices• Stable, warm
temperatures• Microclimate
options• Predator
protection• Replacement
roosts . . . . because, like other species of wildlife, bats are losing natural roosts in caves and forests at a rapid rate and have adapted well to human-made structures
Sports Stadium
Abandoned Warehouse with ¼ million Mx free-tailed bats
Bridges
Dean Gallagher, FFWCC
Dean Gallagher, FFWCC
Culverts & Tunnels
Where Bats Roost—Buildings
• Bats may roost in attics, in dropped ceilings, in boxed eaves and gables, behind siding and masonry, under roof tiles and shingles and behind shutters.
• Bats don’t gnaw on wood or wires, but will use holes or cracks ½” and larger created both by other animals and by deferred maintenance.
Missing or Broken Chimney Caps
Torn Screens on Gable Vents
Where Masonry meets Siding or Cornice
Dormer Soffit / Roof JunctionUnder Loose Shingles
Behind Downspouts & Gutters
Torn Window Screens
Eaves / Soffit Vents
Broken Siding
Basement Doors
Under Window Sills
Where Bats Roost
Tile Roofs
Access Points Intersections
Wall & Roof (along eave and at gable)Dormer & RoofPorch & HouseExpansion Joints
PenetrationsAround poorly sealed pipes, wiring, and
vents going through the exterior of a building
Areas of Disrepair – Broken shingles and windows, torn screens, rotted fascia and soffit
Rock Pocket
Intersections ofDifferent Materials
Signs of Entry
Sometimes indicated by dark stains from body oils around access points
Guano can resemble rodent droppings, but is soft and crumbles easily; Guano contains shiny insect parts and no white material
Piles of guano beneath access points
Sometimes tenants are temporary
• spring and fall migration• newly volant young in summer• through open doors or windows
Ask yourselves:Is exclusion necessary?Is it possible to wait them out, or even to live with the situation?
What Doesn’t Work?
• Ultrasonic Devices
• Mothballs (Napthalene)
• Trap and Release
• Chemicals
• Simply closing entrances after bats exit for the evening
Exclusion: The OnlyReal, Effective Solution
• Identify entry/exits
• Install one-way valves
• Prevent re-entry
• Provide alternate roost(s)• NEVER exclude when flightless pups may be present (mid-April through August)
Courtesy of Fly by Night, Inc.
Bat Houses canaccommodate under 50 bats, or 10s of Thousands (andeverything inbetween!)
Follow these steps:IDENTIFY AREAS OF ENTRY AND EXIT• Inspections should be conducted during early
evening (dusk) and just prior to dawn to locate bats entering or exiting the building.
• Repeat on several nights in most situations, especially during cooler weather.
-- All bats may not leave every night – especially if it is raining or the temperature falls below 50 degrees F.
• After identifying entrances and exits, seal all other potential entry points using caulk, concrete cements made for cracks and crevices, weather stripping, flashing or hardware cloth/polypropylene netting (no larger than ¼”).
Place exclusion tubes (preferred) or netting – if netting, use 1/6” size flexible netting
Leave the devices up for 5-7 days
When you take them off, seal those areas left open by the devices the same way you sealed the other openings previously
Remove guano from interior structures • Large amounts of guano can attract insect and
other pests• Parasites – mites, fleas, bat bugs – dessicant or
insecticide can be used if necessary
Exclusion Information @
www.batcon.org/buildingswww.flybynightinc.org/ bibguidelines.htmUnder “Bats & People” on the Home Page
Bat House Information @
• www.batcon.org/bathouse
• OR
• www.batcon.org• Under “Get Involved” on
the Home Page
Are Bats Protected?
YES . . . . . and NO:Texas Bat Protection Law was enacted by the Texas State
Legislature in 2001 and is described in Section 63.101, Parks and
Wildlife Code
Environmental Protection Agency, Section 24(c) of the
Federal Insecticide, Fungicide and Rodenticide Act
(FIFRA)
But . . . there are lots of ways around existing
regulations, and even in states that offer some
protection, unless it is an endangered or threatened
species, bats in or on buildings where people live and
work are at risk
Aesthetic & Ethical
bats are unique products of millions of years of evolution
humans have demonstrated the capability of forcing bats to extinction … we must do all we can to save bats (Gary McCracken)
WHY SAVE BATS?Intrinsic values
Ecological & Economic
Bats eat crop and forest pests-many pest species are nocturnal so birds are not effective predators
Scientists estimate the million bats lost to White Nose Syndrome in the eastern U.S. would have eaten 694 tons of insects just last year
WHY SAVE BATS?
Utilitarian Values
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